so it goes.. alder mount onto screen bar (that had to be trimmed to fit nicely). Tourtwat mount then bolted to Alder mount (had to re drill the base plate for TT plate). Then Garmin mount in TT anti shake mount.
Right bl88dy pallava but it looks pretty sexy now.... I'll take a pic if you're interested....?
The Alder mount is the best way on a GSA screen and use 'second skin' or a similar protective cover around the bar to save it getting scratched.
The only problem you will have is that due to the shape of the 550 mount your rev counter will be obscured, (easily fixed by buying a Zumo 660).